The present invention relates to turbines, and more particularly relates to blades and other turbine components comprising thin skins bonded to superalloy substrates.
State-of-the-art blades and vanes that are employed in modern, high efficiency power generation combustion turbine engines rely on high quality materials such as single crystal alloys and precise control of the part""s internal and external dimensions. Because of the large size of these parts, cost-effective manufacturing is being pursued by several routes.
Land-based gas turbines, such as the advanced turbine system (ATS) which is currently under development, require cost-effective high performance components fabricated from advanced materials. First and second row turbine blades and vanes include complex internal and external geometries, and should be fabricated from defect-free materials.
Thin wall structures would be useful for modern turbine blade designs in order to improve operating efficiency. However, such thin wall structures greatly inhibit manufacturing of the blades. In particular, the control of thin wall sections over the very long distances that are required for land based turbine airfoils is very difficult, and leads to very low casting productivity and high component costs. These productivity and cost problems are especially severe for the single crystal alloys that are called for in ATS and next generation turbine engines.
In accordance with the present invention, high efficiency thin walled turbine components such as turbine blades are manufactured by fabricating a superalloy substrate such as a single crystal inner spar structure and bonding a thin skin over the substrate. For example, a substrate in the form of a turbine blade airfoil spar may include a corrugated or intermittently raised surface such as raised pins or walls onto which a thin skin can be bonded. The thin skin can be of single crystal or a polycrystalline material, and has a preferred thickness of from about 0.025 to 0.125 cm (0.01 to 0.05 inch). The skin is bonded to the substrate by thermal processes such as transient liquid phase bonding and/or hot isostatic pressing.
An aspect of the present invention is to provide a method of making a thin walled turbine component. The method includes the steps of providing a superalloy substrate including multiple extensions on its surface, applying a thin skin over the substrate, and bonding the thin skin to the extensions of the substrate.
Another aspect of the present invention is to provide a turbine component comprising a superalloy substrate, a thin skin bonded to a superalloy substrate, and at least one cooling channel located between the substrate and the thin skin. In a preferred embodiment, the substrate comprises an airfoil spar made of a single crystal nickel base superalloy.
These and other aspects of the present invention will be more apparent from the following description.